Navigation system



FIG. 1 is a front elevational view of a navigation system showing my newdesign;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a rear elevational view thereof.

The ornamental design for a navigation system, as shown and described.